This invention relates to an electronic endoscope whereby a plurality of endoscopes can be used.
Recently, there is extensively used an endoscope whereby internal organs within a body cavity can be observed by inserting an elongate insertable part into the body cavity or various therapeutic treatments can be made by using treating tools inserted through a treating tool channel as required.
Various electronic endoscopes using a solid state imaging device such as a charge coupled device (CCD) are suggested.
Now, in a conventional video camera, there has been only one kind of pixel size of an imaging device (solid state imaging device) or a number of vertical pixels and horizontal pixels (which shall be mentioned as a pixel formation hereinafter).
However, recently, in an electronic endoscope, the observed parts are more and more manifold and the outside diameter allowed for the endoscope varies depending on the observed part. Particularly, when a comparatively large solid state imaging device such as is used for an electronic endoscope for lower digestive organs, such as the large intestine and small intestine, is used for an endoscope for observing a very fine diameter part such as a bronchus tip or vein, the endoscope will not be able to be made small enough in diameter. Therefore, with only one kind of solid state imaging device as in the past, various observed parts can not be well coped with.
Therefore, a solid state imaging device of a different size must be used in response to the observed part. In such a case, the number of pixels and sensitivity of the solid state imaging device will be different, therefore the switching of a circuit constant, such as an interpolating coefficient will be required and the adjustment of the gain by an automatic gain controlling circuit (which shall be abbreviated as an AGC hereinafter) will be complicated.
Therefore, in order to cope with the above mentioned problems, in the publication of a Japanese patent application laid open No. 179129/1986, there is disclosed a technique wherein a means of storing the information of various conditions, such as the type of endoscope, white balance, number of pixels of the solid state imaging device and sensitivity of the solid state imaging device, is provided on the endoscope body side and the connector on the endoscope body side is connected to the connector on the video processing part side so that the various conditions may be read into a reading-in apparatus on the video processing part side and may be transmitted to a control part to be automatically set.
However, there have been problems that, in the above mentioned conventional technique, so that many conditions may be stored so as to be able to correspond to a plurality of different endoscopes and further an adjustment matching the many conditions may be made automatically, the circuit scale will become large and the cost will become high.